Non-volatile memory (NVM) devices are able to retain stored data even when the power supply is interrupted. Non-volatile memory devices include flash devices which can be programmed using electrical signals. A NVM device, for example, includes a memory transistor and a select or access transistor in series. The memory transistor stores data programmed into the memory cell, while the access transistor selects the memory cell to be programmed or erased.
As technology evolves into era of sub-micron, there is a desire to integrate memory arrays of different voltages, high voltage (HV) devices and high speed logic circuit elements into a single chip or integrated circuit (IC) to form an embedded memory. Nevertheless, it is difficult to integrate these different types of devices in a single chip since each of these devices has different requirements. For example, the memory cell size for higher voltage application is bigger than the memory cell size for lower voltage application. As such, it is necessary to alter or change the processing steps to accommodate for the memory cells with different voltage applications. This, however, may compromise or affect reliability of some of the devices and undesirably complicates the manufacturing process and increases the manufacturing cost.
From the foregoing discussion, it is desirable to provide a reliable, high performing and simplified solution for integrating different types of devices in the same IC.